SIGNIFICANCE OF DISSOLVED OXYGEN LEVELS IN TREATED WATER BEING RELEASED FROM SEWERAGE TREATMENT PLANTS (STP): NANOBUBBLES TREATMENT A SOLUTION

Introduction: Sewage Treatment Plants (STPs) play a crucial role in treating wastewater and ensuring the protection of the environment and public health. However, the current practice of releasing treated water with low Dissolved Oxygen (DO) levels into receiving waters has negative impacts on the environment, contradicting the core environmental objectives of sewage treatment. In this article, we will explore the significance of maintaining adequate DO levels in treated water and its implications for agriculture, river waters, and overall ecosystem health.

The Importance of Dissolved Oxygen Levels: Dissolved Oxygen (DO) is vital for the survival of aquatic life. It is the amount of oxygen dissolved in water and is essential for the respiration of fish, insects, and other aquatic organisms. Low DO concentrations in treated water can have far-reaching consequences, affecting both agricultural practices and the health of river ecosystems.

Impact on Agriculture: Agriculture heavily relies on irrigation water for crop growth and productivity. However, when the treated water released from STPs has low DO concentrations, it can adversely affect plant growth and yield. Plant roots require oxygen to function properly, and inadequate DO levels in irrigation water can reduce the oxygen supply to the roots, leading to stunted growth and decreased crop yields. Additionally, low DO levels in irrigation water can promote the growth of anaerobic bacteria, negatively impacting soil health and causing nutrient loss.

Effects on River Waters: Low DO concentrations in river waters pose significant risks to aquatic life. Fish, insects, and other aquatic organisms depend on oxygen dissolved in water for survival. Insufficient DO levels can lead to reduced growth, reproduction, and survival rates of these organisms. Furthermore, low DO levels can trigger the release of toxic compounds such as ammonia and hydrogen sulfide, further compromising the health of aquatic life. This disruption in the ecosystem can have cascading effects on the entire food chain and biodiversity.

Hypoxia and Algal Blooms: When water with low DO levels is discharged into receiving water bodies, it can lead to a condition known as "hypoxia," where oxygen levels become critically low, making it impossible for aquatic life to survive. Hypoxia can result in fish killings, loss of other aquatic organisms, and overall ecosystem disturbance. Additionally, low DO concentrations contribute to the growth of algae and other microorganisms, leading to the formation of harmful algal blooms. These blooms can release toxins that pose risks to both humans and animals, further exacerbating the environmental impact.

The Need for Regulation and Monitoring: To address the significance of DO levels in treated water, regulatory agencies should establish and enforce minimum DO level requirements for water discharged from STPs into receiving waters. These regulations would ensure that STPs prioritize maintaining DO concentrations that are sufficient to support aquatic life and protect the environment. Additionally, it is crucial to include the measurement and monitoring of DO levels, with a recommended minimum of 4 PPM, as a key performance indicator (KPI) for treated water discharged from all STPs. This monitoring process will help ensure compliance, early detection of anomalies, and timely corrective actions.

Conclusion: The significance of dissolved oxygen levels in treated water released from STPs cannot be overstated. Adequate DO concentrations are essential to safeguard agriculture, protect river ecosystems, and maintain a healthy environment. It is imperative for STP plants to prioritize maintaining DO levels in compliance with local regulations to ensure the sustainability of our water resources and the preservation of aquatic life. By acknowledging the importance of DO levels in treated water, we can take significant steps towards achieving a more environmentally responsible and sustainable approach to wastewater management.

The Potential of Nanobubbles Treatment as a Solution:

In the quest for addressing the issue of low Dissolved Oxygen (DO) levels in treated water from Sewage Treatment Plants (STPs), one promising solution is the application of nanobubbles treatment. Nanobubbles are tiny gas bubbles with diameters in the nanometer range that exhibit unique physical properties, including long-lasting stability and high gas dissolution efficiency. Incorporating nanobubbles treatment into the existing wastewater treatment processes can offer several benefits:

Enhanced Oxygen Transfer Efficiency: Nanobubbles have a significantly larger surface area-to-volume ratio compared to conventional bubbles, allowing for greater gas-liquid contact. This increased contact area enhances the transfer of oxygen from the nanobubbles into the water, leading to higher DO concentrations. By utilizing nanobubbles treatment, STPs can significantly improve the oxygen transfer efficiency and elevate DO levels in the treated water.

Longer Dissolved Oxygen Retention: One of the remarkable properties of nanobubbles is their prolonged retention time in water. Unlike larger bubbles that rise quickly to the surface and release the dissolved gas into the atmosphere, nanobubbles remain suspended for extended periods. This extended retention time allows for continuous oxygen release and sustains elevated DO concentrations in the treated water, even during storage and transport.

Reduction in Energy Consumption: Implementing nanobubbles treatment can potentially reduce energy consumption in STPs. Traditional methods of increasing DO levels often involve mechanical aeration systems that require substantial energy inputs. Nanobubbles, on the other hand, can achieve comparable or even higher DO concentrations with significantly reduced energy requirements. This energy efficiency makes nanobubbles treatment an attractive and sustainable solution for STPs.

Enhanced Nutrient Removal: Nanobubbles treatment not only increases DO levels but also enhances the removal of nutrients such as nitrogen and phosphorus during wastewater treatment. The presence of elevated DO concentrations promotes the growth of beneficial aerobic microorganisms that facilitate the breakdown of organic matter and the removal of nutrients. This dual benefit of nanobubbles treatment contributes to improved water quality and reduced environmental impacts.

Recommendation: Considering the potential of nanobubbles treatment in addressing the low Dissolved Oxygen levels in treated water, it is recommended that STPs explore the integration of this technology into their existing wastewater treatment processes. Pilot-scale studies and collaborations with technology providers specializing in nanobubbles treatment can be initiated to assess its effectiveness, feasibility, and economic viability for specific STP setups.

Regulatory bodies and stakeholders should also support research and development efforts focused on nanobubbles treatment, incentivizing its adoption in wastewater treatment facilities. This would involve establishing guidelines and standards for the use of nanobubbles treatment in STPs, along with monitoring protocols to ensure compliance and evaluate the long-term environmental and economic benefits.

By embracing nanobubbles treatment as a solution, STPs can significantly enhance the dissolved oxygen levels in treated water, mitigate environmental risks, and promote sustainable wastewater management practices. The integration of this innovative technology has the potential to revolutionize the industry and contribute to a healthier and more environmentally conscious future.